Retention of hydrophobicity under DC voltage stress Evaluation with the dynamic drop test

Polymeric high voltage insulators are applied in all voltage levels under AC as well as under DC voltage stress.  They are considered reliable and in some aspects even superior to ceramic insulators and correspondingly their share in the insulator market is considerable. Housing materials for outdoor insulation are predominantly silicone rubbers (SiR), ethylene propylene diene monomer (EPDM) and ethylene-vinyl acetate rubbers (EVA). For indoor insulation cycloaliphatic epoxies are commonly used [1]. The applied materials have to provide minimum requirements in respect to all relevant properties, which should be verified by suitable test methods. Based on the work of CIGRE WG D1.14 the technical report IEC/TR 62039 was developed, which defines twelve important physical properties for…